Motor vehicle friction clutches provide a selectively engagable frictional connection between an engine crank shaft and a motor vehicle transmission. A clutch driven disc with friction material is rotatably fixed to an input shaft of the transmission and is axially disposed between a flywheel fixed to the engine crank shaft and a clutch pressure plate. A cover is disposed over the pressure plate and is rigidly clamped to the flywheel. The pressure plate is connected to the cover by a flexible strap which enables axial movement of the pressure plate toward and away from the cover while preventing rotation of the pressure plate relative to the cover and flywheel.
The pressure plate is biased toward the flywheel and against the driven disc by one or more clutch springs. The clutch springs act against the pressure plate to hold the pressure plate against the flywheel. Known alternative embodiments of clutch springs include a diaphragm spring acting directly against the pressure plate, and, alternatively, a plurality of coil springs acting indirectly against the pressure plate through intervening mechanisms such as a retainer and a plurality of levers. Each embodiment has an associated means of selectively relieving the spring load. Diaphragm springs commonly have a plurality of radially inwardly extending fingers engaged by a clutch release and housing assembly. Coil springs have the retainer connected to the bearing and housing assembly for axial movement therewith. With either configuration, the spring load of the pressure plate against the driven disc is relieved by axially displacing the bearing and housing assembly axially along the transmission input shaft.
Bearing and housing assemblies for use in medium duty and heavy duty trucks include a plurality of features integrated into the bearing housing which allow the outer race of the bearing to be self aligning to a limited degree with respect to the inner race of the bearing, thereby evenly distributing the load within the bearing. Such alignment is important in prolonging bearing life. Alignment is achieved by enabling a limited amount of pivoting of the outer race about two axes. One pivot axis extends between two ears of the housing which are engaged by a clutch fork (not shown). The other pivot axis is defined by a pair of pivot pads disposed on a surface forming an end of the housing. The pivot pads are spaced approximately 180.degree. apart from each other and are located for engagement by an end of the release bearing's outer race. A pair of axially extending radial engagement or contact teeth extending radially inwardly from an inner circumference of the housing. These teeth are located approximately 90.degree. apart from each other and are equally spaced from the pivot pads. A flat wire spring, disposed between the housing and the outer race opposite the contact teeth, radially biases the outer race into engagement with the contact teeth. The contact teeth serve to limit radial contact between the outer race and the bearing housing. Limiting the radial contact facilitates pivoting of the outer race about the axis extending between the two pivot pads.
The above described bearing and housing assembly works well when the bearing and housing assembly is new. However, with use, the engagement teeth and the pivot pads begin to wear due to slippage of the outer race relative to the housing. When the engagement teeth wear to a point where the outer race also contacts the housing midway between the teeth, the outer race pivots less easily about the axis between the pivot pads. Further, when the pivot pads wear, the available amplitude of pivoting of the outer race is greatly reduced.
Typically, the contact teeth and the pivot pads are formed as-cast in the bearing housing. When the contact teeth and/or the pivot pads deteriorate to the point where pivoting as desired is no longer possible, the release bearing and housing assembly is often remanufactured (remanned). The housings are remanned by installing rivets to replace worn pads and teeth in the housing. A high level of dimensional control is not required, as the pivoting effect is present over a significant range of tooth and pad dimensions. However, the cost of drilling and riveting associated with the above described method of remanning is undesirably high and, in some cases, is not feasible. In the case of particularly severe wear, it is necessary to scrap the housing.
It is desired to provide an implement replacing worn features within a clutch bearing housing which is both easy to install and inexpensive.
It is also desired to provide an inexpensive method of remanufacturing bearing and housing assemblies.
It is also desired to provide a method of remanufacturing of bearing and housing assemblies enabling the remanufacture of bearing and housing assemblies using housings which would otherwise be scrapped.